[llvm] [AVR] Add intrinsics for builtin functions (PR #203212)

[Ben Shi via llvm-commits]

================
@@ -0,0 +1,24 @@
+//==- IntrinsicsAVR.td - AVR intrinsics                 -*- tablegen -*-==//
----------------
benshi001 wrote:

It would be better if the first can be 
```
//===- IntrinsicsAVR.td - Defines AVR intrinsics ------------*- tablegen -*-==//
```

https://github.com/llvm/llvm-project/pull/203212